Trader Michael Zicchinolfi, left, and specialist Frank Masiello work on the floor of the New York Stock Exchange, Thursday, April 3, 2014. Stocks indexes are edging higher as investors become more optimistic about the outlook for the U.S. economy. (AP Photo/Richard Drew) ORG XMIT: NYRD107

Trader Michael Zicchinolfi, left, and specialist Frank Masiello...

Traders work on the floor of the New York Stock Exchange, Thursday, April 3, 2014. Stocks indexes are edging higher as investors become more optimistic about the outlook for the U.S. economy. (AP Photo/Richard Drew) ORG XMIT: NYRD108

Traders work on the floor of the New York Stock Exchange, Thursday,...

Trader Frederick Reimer, foreground, on the floor of the New York Stock Exchange, Thursday, April 3, 2014. Stocks indexes are edging higher as investors become more optimistic about the outlook for the U.S. economy. (AP Photo/Richard Drew) ORG XMIT: NYRD106

The stock market held close to its all-time high on Thursday amid optimism that the economy is set to strengthen.

Stocks are on course for their best weekly gain in seven weeks after investors got more encouraging news on the economy. A survey showed that U.S. service firms increased their business more quickly last month as new orders rose. Separate reports earlier in the week had shown manufacturing strengthening, hiring picking up, and sales of cars and trucks rising.

The news came ahead of the government's monthly jobs report, which will be published Friday.

"If you have a decent economy, a modestly growing economy, that's supportive of corporate earnings and stocks can continue to benefit from that," said John Fox, director of research at Fenimore Asset Management.

The Standard & Poor's 500 index fell 2.13 points, or 0.1 percent, to 1,888.77. The index closed at an all-time high of 1,890 a day earlier after rising for four straight days. The Dow Jones industrial average fell 0.45 point, or less than 0.1 percent, to 16,572.55. The Nasdaq composite fell 38.72 points, or 0.9 percent, to 4,237.74.

Stocks started the day higher after getting a lift from a report on the U.S. service sector, a broad category of businesses that includes banks, transportation and construction.

The Institute for Supply Management's non-manufacturing index rose to 53.1 in March, up from 51.6 in February, indicating that growth in the service sector is picking up. The survey also showed hiring picking up.

However, by midmorning stocks started to drift lower. Investors seemed unwilling to place big bets on the market before Friday's key jobs report.

"Going into the employment report, a lot of people aren't anxious to open new positions," said J.J. Kinahan, chief strategist with TD Ameritrade. "They don't want to be taken by surprise."

The stock fell $2.99, or 13.5 percent, to $19.12 after Liberty Media said it was cutting its stake in the company. Liberty Media, the investment company controlled by billionaire John Malone, gave Barnes & Noble a lifeline in 2011 when it bought a 17 percent stake in the company.

Biotechnology stocks also fell.

After surging at the start of the year, biotech stocks have become volatile amid concerns about the cost of the drugs that they're developing.

The S&P's index of biotechnology stocks fell 1.6 percent, paring its gains for the year to about 1.2 percent.

The Class A shares, which have been traded since the company went public nearly a decade ago, now trade under the ticker symbol "GOOGL." The Class C shares inherited the "GOOG" ticker symbol.

In government bond trading, bond prices rose. The yield on the 10-year Treasury note fell to 2.79 percent from 2.80 percent on Wednesday.

The price of oil rose 67 cents, or 0.7 percent, to $100.29 a barrel. Gold fell $6.20, or 0.5 percent, to $1,284.60 an ounce

Among other stocks making big moves:

Anadarko Petroleum jumped $12.55, or 14.5 percent, to $99.02 after the company announced that it had reached a $5.15 billion deal to settle claims arising from the 2009 bankruptcy of paints materials maker Tronox. A U.S. bankruptcy court judge said in December that Anadarko Petroleum may be liable for between $5 billion and more than $14 billion in the legal battle.